This invention relates to a method of reclaiming aluminum from aluminum-glass cloth residues.
In pouring molten aluminum into various solid shapes suitable for rolling or extrusion operations, the molten aluminum passes through a woven glass cloth filter. The purposes of this filtering is to minimize the number of hard particles e.g. aluminum borides and aluminum oxides, contained in the molten metal from entering the solid shape. Such a procedure using a glass cloth filter is described in Canadian Pat. No. 554,853 issued Mar. 25, 1958.
This filtering technique is widely used throughout the aluminum industry and a significant amount of metal freezes on the glass cloth on completion of each pour of molten aluminum. The usual method for recovering the aluminum deposited on the glass cloth is by differential melting whereby the glass cloth with the deposited aluminum is heated to a temperature at which the aluminum melts but below the point at which the glass cloth melts. This combined with differences in specific gravity results in their separation, the glass cloth rising to the surface of the bath to be skimmed off as part of the "dross." This has been done either by returning the aluminum-glass cloth residues to the melting furnace from which the aluminum has passed through the glass cloths or it is even sometimes done in totally different locations.